Hello,
I have a problem: I have replaced a police car with a light bar (NOT ELS) with the fbi buffalo, but when i press to activate the lights, they work only on the frontal part of the light bar and not on the rear.
Someone can help me please!?
Thanks

I'm having this problem too. I've tried using several cars of this site, but the lights do not work. It's funny because when I use play car lights work but the car is a mod, it does not work. The siren sounds but the lights do not work.
Could you help me?

You say one ambulance or fire truck? But the system would not be the same?
You're right. The cars that do not use this feature work. But the coolest police cars use this feature.
There's no way I use it?

No you can't use those ELS vehicles without the ELS mod (they won't function atleast). If you really want them I'd suggest trying to install the ELS mod again, just make sure you've updated your game and got the right files. I'm sure it's all there in the readme